1. Abstract

There are a number of models for sound field calculations. They include analytical, partly analytical [1] and numerical methods [2]. As far as they refer to sound fields of pulsed sources, their results are often given in so called snapshots, i.e. images of sound field values at a fixed time (see [2] for an example). An other word for that type of mapping, used here as a synonym, is stroboscopic imaging. These images are helpful for understanding the physics of sound field propagation and the interaction of sound fields with defects.

Only a few experimental methods are known which generate these ultrasound wave images but they are either limited in its applicability or very expensive. The aim of this paper is therefore twofold: Firstly existing methods of experimental production of sound field images will be reviewed. Secondly new and rather inexpensive method for sampling of stroposcopic pictures is given. Our considerations are limeted to sound fields in solids and on their surfaces.

The article provides a demonstration of a movie-file "rayleigh.mpg". The file can be viewed with any MPEG viewer.
The movie shows a 10 second length of a 2 Mhz Rayleigh wave hidden between two notches on a AL-plate. The movie file can be downloaded from the SWRI South West Research Institute server - URL: ftp://ftp.nde.swri.edu/pub/nde/ultrasonic_fields/rayleigh.mpg
You can download it now also => Download rayleigh.mpg movie 750KB

Content |Full Text|

1. Abstract
2. METHODS OF VISUALISATION OF SOUND FIELDS
3. PRINCIPLE OF STROBOSCOPIC MEASUREMENTS
4. EXAMPLES OF APPLICATIONS
5. SUMMARY
6. Literatur

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